This invention relates notably to a secure article, notably a security and/or valuable document, and a material for achieving such an article.
Security and/or valuable documents are known, comprising security elements enabling to protect these documents against any forgery or counterfeit attempt.
Among the security elements, some of them can be detected with the naked eye, in visible light, without using any specific apparatus. These security elements comprise for example one watermark, some coloured fibres or flakes, some printed, metallic or holographic yarns, some holographic foils or some prints with variable optical effect.
These security elements are said to be of first level.
Other types of security elements can only be detected using a relatively simple apparatus such as a UV or infrared-emitting lamp. These security elements comprise for instance fibres, flakes, strips, yarns or particles. These security elements can be visible to the naked eye or not, being luminescent under the lighting of a Wood lamp, emitting in a wavelength of 365 nm for example.
These security elements are said to be of second level.
Other types of security elements still require a more sophisticated detector for their detection. These security elements are, for instance, able to generate a specific signal when they are submitted, simultaneously or not, to one or more external excitation sources. The automatic detection of the signal enables to authenticate the document, if necessary.
These security elements comprise, for example, some tracers in the form of active material, particles or fibres, able to generate a specific signal when these tracers are submitted to an optoelectronic, electric, magnetic or electromagnetic excitation.
These security elements are said to be of third level.
Some tracers randomly scattered within the document can serve to identify, by forming a single signature of the document, based, for instance, on the intensity and/or the type of signal generated by the tracers, considered individually and/or together, the density of tracers or the geographical distribution of tracers in a predefined zone of the document.
Some tracers that can be used for identifying a document, comprising, for example, soft magnetic fibres whose response to an external magnetic field is non-linear, the magnetization of fibres varying according to the hysteresis loop. A set of fibres present in a predetermined zone of the document enables to delimit a single signature of the document because of the distribution, the orientation and the random number of fibres existing in the above-mentioned zone. In the case of a passport and notably a visa page, the magnetic fibres can be present on a page in which the customization related to the passport holder is achieved. This customization, according to the ICAO (International Civil Aviation Organization) recommendations comprises the printing of one coded line in the page border from customization data. This OCR (Optical Character Recognition) line is automatically controlled by an appropriate optical control system. The optical control system can be adapted, so that when reading the OCR line, an identification of the signal generated under a magnetic field by the magnetic fibres present in the inspected zone by the optical control system could be also carried out.
The tracers composed of metallic fibres having a specific response by reflection and by transmission to an excitation of microwave type, can still be used.
The tracers marketed under the name of Trace-less™ by the CREO Company are also known. These tracers consisting of particles are invisible after insertion into the document to be protected and can be detected thanks to a specific electromagnetic response when submitted to an excitation in the field of infrared. The enabled identification of a document comprising such particles is based on the verification of the particles distribution in a predefined zone, this verification being notably carried out by means of an image of particles observed under an appropriate electromagnetic source. The considered inspection zone can rely, for example, on the character outline that is printed on the document at a later date.
The microscopic particles marketed under the name of Nanoplex® by the NANOBARCODES Company can be used in a document for identification through optical analysis of an image. These particles present a cylinder shape with variable reflectance zones obtained by stacking different metals, which enables to create varied optical codes according to the sequence of metals used. The detection of particles on a document for authentication is carried out by means of an optical microscope. The identification of document can, further, be automatically carried out by randomly incorporating on the latter, particles of different codes, and by checking through image analysis, for a predetermined zone of the document, the respective percentage of each type of particles and their spatial distribution in the above-mentioned zone.
For a document incorporating excitable luminescent particles through a radiation at 365 nm, marketed under the name of Polystar™ by the SPECTRA SYSTEMS Company, the document identification is carried out with a portable system fitted with a digital camera, marketed under the name of Vericam™, by analysing the spectral emission, namely the fluorescence “colour” of particles, as well as the density of particles for each of the “colours”.
The HYPERLABEL TECHNOLOGIES Company has developed an active material. Formulated in an ink, this one is printed by ink jet printing on a document or article to be traced, in the form of a microscopic code of matrix code type. This invisible code is presently printed in a redundant manner in certain sections of the document to be traced to make the identification process possible, even if the code on the document surface is partly altered, as well as to facilitate this identification process notably because of the tolerance in placing a reading system on the zone to be controlled. The code is read by means of a system equipped with a digital camera functioning in infrared. The inspection zone of the printed code is defined thanks to the printing of specific marks around each code, each code being located as it were, in the middle of a box of a grid with marked intersections. This way of delimiting the inspection zone by printing can constitute, in some cases, a constraint.
The document entitled “Secure fingerprint of packaging and documents without tags, chips or ink” by Russel Cowburn from the Imperial College of London discloses a method for reading one paper signature by using the scanning of a paper zone in order to determine the 3D topography of the paper. The scanned paper zone rests on a border and/or corner of the paper. When the border or the corner is damaged, the reading becomes more difficult, even impossible.
The international application WO 2005/025891 discloses a banknote comprising on one side a holographic strip with windows, through which some identifying elements such as a watermark or fluorescent particles can be detected.
The patent application US 2004/0113420 discloses a card comprising one plastic substrate. Fibres are scattered at random on one substrate side while being slightly squeezed in the substrate mass. A metallic layer is formed on this substrate side, so that it could partly cover the fibres. The metallic layer comprises windows for detecting the fibres. The card identification is carried out by detecting the presence of fibres through the above-mentioned windows by scanning according to one or more straight lines by means of a detection device.
The application FR 2 324 060 further discloses a paper and/or synthetic document, incorporating magnetic fibres scattered at random within the document. The document authentication relies on the detection of fibres in the scanning zone, by means of a magnetic head.
The application FR 2 765 014 discloses a paper document incorporating magnetic flakes. The document comprises an invisible bar code directly linked to the random distribution of flakes in a zone of the document.
The application GB 2 324 065 A discloses a tag including randomly scattered particles. This tag can be incorporated into a banknote during manufacturing, and consequently it is not necessarily visible by reflection to the naked eye or with a magnifying glass or any other magnifying accessory. A code associated with the distribution of particles can be stored in a database with the banknote serial number. In this application, the position of particles is measured in both dimensions for example, by being located with respect to one line, or in the three dimensions.
The U.S. Pat. No. 4,114,032 patent describes a document incorporating magnetic fibres, the reading of a signal linked to these fibres is carried out according to a specific path.
Notably, there is a need to improve the identification method and make it reliable by automatic reading of tracers inserted into a substrate and also to further strengthen the protection of security and/or valuable documents against forgery and counterfeit.